Headache is essentially a universal human experience. It is the most common complaint among new patients seeking neurological consultation worldwide. Although the brain itself lacks pain receptors, various anatomical structures that surround it are particularly sensitive; it is largely these, non-neural structures (especially the vessels and the dura), that are ultimately responsible for the generation of pain.
There are many different types of headache, each having its own clinical characteristics and treatment response. A headache may appear sporadically or daily; it may have sudden or gradual onset; it may last a few seconds or days; the pain may be mild or excruciating. For some people, headache is just an occasional annoying experience, whereas for others it is a major source of suffering, disrupting their quality of life.
According to the International Headache Society, headaches and facial pain can be classified into 3 major groups:
1. Primary headaches
These types of headache are seen in the absence of any exogenous cause. The painful syndrome constitutes the entire disorder by itself. Consequently, they are not related to any serious underlying disease or process. Primary headaches make up the vast majority of cases. The most common types are the following:
2. Secondary headaches
These types of headache are induced by an exogenous factor. Although they are less frequent than primary headaches, some of them may be caused by serious underlying conditions that necessitate urgent medical attention.
Examples are headaches due to subarachnoid hemorrhage, arterial dissection or meningitis. However, a significant proportion of secondary headaches are benign (i.e. related to sinusitis, analgesic overuse, etc).
3.Cranial neuralgias, facial pains & other headaches
This is a heterogeneous group of conditions that cause pain in the head or face, the most common being trigeminal neuralgia.